Kinetic energy of fragment ions by pulsed laser-pulsed extraction field technique and the mechanism of laser multiphoton ionization dissociation: 2,4-hexadiyne

1988 ◽  
Vol 92 (19) ◽  
pp. 5333-5337 ◽  
Author(s):  
M. A. El-Sayed ◽  
Tsong Lin Tai
Keyword(s):  
Kinetic Energy ◽  
Multiphoton Ionization ◽  
Pulsed Laser ◽  
Field Technique ◽  
Extraction Field ◽  
Fragment Ions

Low-Fluence Laser Induced Fragmentation and Desorption of 3,4,9,10-Perylenetetracarboxylic Dianhydride (PTCDA) Thin Film

2013 ◽  
Vol 543 ◽  
pp. 30-34 ◽  
Author(s):  
Aljona Ramonova ◽  
Tengiz Butkhuzi ◽  
Viktorija Abaeva ◽  
I.V. Tvauri ◽  
Soslan Khubezhov ◽  
...  
Keyword(s):  
Thin Film ◽  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Kinetic Energy ◽  
Atomic Oxygen ◽  
Laser Light ◽  
Pulsed Laser ◽  
Molecular Fragmentation ◽  
Irradiation Pulse ◽  
Main Effect

Laser-induced fragmentation and desorption of fragments of PTCDA films vacuum-deposited on GaAs (100) substrate has been studied by time-of-flight (TOF) mass spectroscopy. The main effect caused by pulsed laser light irradiation (pulse duration: 10 ns, photon energy: 2.34 eV and laser fluence ranging from 0.5 to 7 mJ/cm2) is PTCDA molecular fragmentation and desorption of the fragments formed, whereas no desorption of intact PTCDA molecule was detected. Fragments formed are perylene core C20H8, its half C10H4, carbon dioxide, carbon monoxide and atomic oxygen. All desorbing fragments have essentially different kinetic energy. The mechanism of photoinduced molecular fragmentation and desorption is discussed.

Ion Kinetic Energy Distributions and Mechanisms of Pulsed Laser Ablation on Al

2008 ◽  
Vol 112 (42) ◽  
pp. 16556-16560 ◽  
Author(s):  
Jon I. Apiñániz ◽  
Borja Sierra ◽  
Roberto Martínez ◽  
Asier Longarte ◽  
Carolina Redondo ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Kinetic Energy ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Energy Distributions ◽  
Ion Kinetic Energy ◽  
Kinetic Energy Distributions

scholarly journals Multiphoton Ionization Mass Spectrometric (MPIMS) Study of Phenol: Mechanism of Ionic Fragment Formation

1983 ◽  
Vol 3 (1-6) ◽  
pp. 29-47 ◽  
Author(s):  
R. S. Pandolfi ◽  
D. A. Gobeli ◽  
Jonathan Lurie ◽  
M. A. El-Sayed
Keyword(s):  
Laser Pulse ◽  
Energy Levels ◽  
Multiphoton Ionization ◽  
Pulsed Laser ◽  
Ionic Species ◽  
Low Energy ◽  
Ionization Mass ◽  
Fragmentation Pattern ◽  
Dissociation Channel ◽  
532 Nm

Time of flight (TOF) mass spectrometry is used in conjunction with a variable repelling voltage technique to elucidate the mechanism by which phenol ionizes and dissociates under 266 nm pulsed laser irradiation in combination with a 532 nm or 355 nm pulsed laser. The results suggest that, like benzene, the molecular ion is the predominant precursor of all ionic species generated in the process. Predominance of C5Hx+ species at relatively low powers confirms the presence of a low energy dissociation channel involving the elimination of CO. The use of a second laser at 532 nm is found to selectively destroy the C5Hx+ (as compared to the parent ion) species. The parent ion is found to be protected from the radiation of the second laser pulse at 532 nm but not at 355 nm if the second laser pulse is delayed by 50 ns. This is explained in terms of relaxation within the parent ion energy levels, the location of a low energy dissociation channel and the wavelengths of the lasers used. The main aspects of the fragmentation pattern are discussed in terms of the statistical theory of Rebentrost and Ben-Shaul.

Rearrangements in the Molecular Ions of Some ortho-Substituted Schiff Bases

1993 ◽  
Vol 46 (6) ◽  
pp. 895 ◽  
Author(s):  
T Blumenthal ◽  
M Dosen ◽  
RG Gillis ◽  
QN Porter
Keyword(s):  
Kinetic Energy ◽  
Schiff Bases ◽  
Molecular Ions ◽  
Energy Spectra ◽  
Supporting Evidence ◽  
Deuterium Labelling ◽  
Methyl Group ◽  
Molecular Ion ◽  
Fragment Ions ◽  
Ion Kinetic Energy

Under electron ionization conditions, the ortho-substituted Schiff bases N-benzylidene-o-toluidine (1a), N-(o-methylbenzylidene)aniline (1b), N-salicylideneaniline (1c) and N-(o-methoxybenzylidene)aniline (1d) give fragment ions which have been shown by collision-activated mass-analysed ion kinetic energy spectra to have the structure of the protonated molecular ions of indole (2), benzofuran (3), and 1,2-benzisoxazole (4). The molecular ion of N-(o-methylbenzylidene)-o-toluidine (1f) gives as fragment ions not only the protonated molecular ion (2) of indole and the tropylium ion but also the molecular ion of anthracene. Attempts to find supporting evidence for a mechanism for this rearrangement by deuterium labelling of a methyl group in (1b), such as (1g), have been unsuccessful.

Sign in / Sign up

Export Citation Format

Share Document